User: | Open Learning Faculty Member:
I have made several changes to my data collection strategy since last time. While I am still using a haphazard sampling method with the help of Google maps, and point counts for estimating Black-billed magpie abundance in relation to human presence in Edmonton’s Hermitage park, I have moved to a dependent double-observer approach. Also, I have reduced the time frame spent at each point count to 20 minutes. There was an additional one-minute settling time given at each point, and five minutes were given to walk from one point to another. Additionally, I have chosen to assess human presence solely by recording the number of pedestrians observed during given time frame. Doing so resulted, I believe, in less bias than recording various predefined “human traces”. Moreover, this time, I chose to record separately: 1. No. of birds seen within the first 5 minutes, 2. No. of birds seen flying over. Doing so will give the reader an idea of whether the presence of observers might have attracted more birds after the first five minutes. Birds seen flying over are generally noted separately in current similar literature, because they cannot be recorded in standard density calculations (Gregory et al. 2004).
To increase the accuracy of my results, I have increased the number of point counts from five to nine which I sampled on two different days (March 24th and March 28th 2018).
As I will explain further in my final report, my literature review as well as previous comments on my past assignments has led me to make those changes. My intention was to minimize bias, standardize my sampling as much as possible, and increase the use of randomization/replication in my sampling strategy. Using a dependent double-observer approach made it much easier to implement my sampling design. Not only did it reduce observer bias, less coordination was needed than it was using different observers for each point count. The only problem encountered was that most of the time, the walking time took a bit less than five minutes, so the real “settling time” was more than a full minute at most points. It was hard to keep track of the exact time spent at each location for that reason.
Gregory, R. D., D. W. Gibbons, and P. F. Donalds. 2004. Bird census and survey techniques. Pages 17–55 in R. E. Green, W. J. Sutherland, and I. Newton. Bird ecology and conservation: a handbook of techniques. Oxford University Press, New York, New York, USA.
